Bluesign: Internal Emulator

[jordanschalm]

This PR replaces the dependency on flow-emulator with a slimmed-down internal Emulator, created by @bluesign. I've made fairly minor changes to the PoC to pass CI.

• Bluesign's PoC in this commit range
• Addressing lint errors (mainly goimports and mod file tidying) in this commit range

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 54.76190% with 1121 lines in your changes missing coverage. Please review.

Project coverage is 41.31%. Comparing base (1d55978) to head (874f633).
Report is 100 commits behind head on master.

Files with missing lines	Patch %	Lines
integration/emulator/mocks/emulator.go	0.00%	257 Missing ⚠️
integration/emulator/blockchain.go	70.53%	166 Missing and 47 partials ⚠️
integration/emulator/mocks/emulatorStorage.go	0.00%	171 Missing ⚠️
integration/emulator/sdk.go	50.15%	140 Missing and 26 partials ⚠️
integration/emulator/memstore.go	69.33%	55 Missing and 14 partials ⚠️
integration/emulator/errors.go	16.90%	59 Missing ⚠️
integration/emulator/convert.go	78.03%	48 Missing and 8 partials ⚠️
integration/emulator/config.go	55.37%	52 Missing and 2 partials ⚠️
integration/emulator/ledger.go	72.63%	18 Missing and 8 partials ⚠️
integration/emulator/emulator.go	40.54%	21 Missing and 1 partial ⚠️
... and 3 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6592      +/-   ##
==========================================
+ Coverage   41.16%   41.31%   +0.15%     
==========================================
  Files        2031     2050      +19     
  Lines      179463   182549    +3086     
==========================================
+ Hits        73869    75419    +1550     
- Misses      99381   100806    +1425     
- Partials     6213     6324     +111     

Flag	Coverage Δ
unittests	41.31% <54.76%> (+0.15%)	⬆️

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[jordanschalm]

Closing in favour of #6594